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Abstract Increasing the thickness of the electrodes is considered the primary strategy to elevate battery energy density. However, as the thickness increases, rate performance, cycling performance, and mechanical stability are affected due to the sluggish ion transfer kinetics and compromised structural integrity. Inspired by the natural hierarchical porous structure of trees, electrodes with bioinspired architecture are fabricated to address these challenges. Specifically, electrodes with aligned columns consist of tree‐inspired vertical channels, and hierarchical pores are constructed by screen printing and ice‐templating, imparting enhanced electrochemical and mechanical performance. Employing an aqueous‐based binder, the LiNi0.8Mn0.1Co0.1O2cathode achieves a high areal energy density of 15.1 mWh cm−2at a rate of 1C at mass loading of 26.0 mg cm−2, benefitting from the multiscale pores that elevated charge transfer kinetics in the thick electrode. The electrodes demonstrate capacity retention of 90% at the 100th cycle at a high current density of 5.2 mA cm−2. To understand the mechanisms that promote electrode performance, simplified electro‐chemo‐mechanical models are developed, the drying process and the charge‐discharge process are simulated. The simulation results suggested that the improved performance of the designed electrode benefits from the lower ohmic overpotential and less strain gradient and stress concentration due to the hierarchical porous architecture.
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Pore Microstructure Impacts on Lithium Ion Transport and Rate Capability of Thick Sintered Electrodes
Increasing electrode thickness is one route to improve the energy density of lithium-ion battery cells. However, restricted Li+ transport in the electrolyte phase through the porous microstructure of thick electrodes limits the ability to achieve high current densities and rates of charge/discharge with these high energy cells. In this work, processing routes to mitigate transport restrictions were pursued. The electrodes used were comprised of only active material sintered together into a porous pellet. For one of the electrodes, comparisons were done between using ice-templating to provide directional porosity and using sacrificial particles during processing to match the geometric density without pore alignment. The ice-templated electrodes retained much greater discharge capacity at higher rates of cycling, which was attributed to improved transport properties provided by the processing. The electrodes were further characterized using an electrochemical model of the cells evaluated and neutron imaging of a cell containing the ice-templated pellet. The results indicate that significant improvements can be made to electrochemical cell properties via templating the electrode microstructure for situations where the rate limiting step includes ion transport limitations in the cell.
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- Award ID(s):
- 1825338
- PAR ID:
- 10309532
- Date Published:
- Journal Name:
- Journal of the Electrochemical Society
- Volume:
- 168
- ISSN:
- 0013-4651
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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